Tag: physics

Questions Related to physics

When a drop of water is introduced between the glass plate and plano-convex lens in Newton's rings system, the ring system

newton's colour disc light and the formation of shadows physics

  1. Contracts

  2. Expands

  3. Remains same

  4. First expands then contracts

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Correct Option: A
Explanation:

The diameter of Newton's rings is inversely proportional to refractive index. Therefore when a drop of water is introduced between the glass plate and plano-convex lens in Newton's rings, the ring system contacts. 

Rainbow is observed when the Sun is 

newton's colour disc light and the formation of shadows physics

  1. In front of the observer

  2. Behind the observer

  3. Vertically above the observer

  4. In any of these position

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Correct Option: B
Explanation:

The sun is always behind the observer. This is because the rainbow is actually just sunlight which has been refracted and reflected.

In the Newton's rings set up, when a drop of water is introduced between the glass plate and planoconvex lens the observed ring system

newton's colour disc light and the formation of shadows physics

  1. Contracts

  2. Expands

  3. Remains the same

  4. Expands and then contracts

Show answer
Correct Option: A
Explanation:

Since diameter of the ring is inversely proportional to the square root of refractive index of the medium between the planoconvex lens and plane glass plate, therefore as refractive index increases, diameter of the rings decrease, that is the rings contract. 

In Newton's experiment the radii of the $m^{th}$ and $(m+4)^{th}$ dark rings are respectively $\sqrt{5}$mm and $\sqrt{7}$mm. What is the value of m?

newton's colour disc light and the formation of shadows physics

  1. $2$

  2. $4$

  3. $8$

  4. $10$

Show answer
Correct Option: D
Explanation:

Radius of mth dark fringe   $r _m = \sqrt{mR\lambda}$
Thus we get  $r _{m+4} = \sqrt{7} = \sqrt{(m+4)R\lambda}$     ......(1)
Also,  $r _m = \sqrt{5} = \sqrt{mR\lambda}$      .......(2)
Dividing equation (1) with equation (2),  
$ \sqrt{\dfrac {m+4}{m} }= \sqrt{\dfrac{7}{5}}$
$\dfrac{m+4}{m} = \dfrac{7}{5}$
$5(m+4)= 7m$
$5m+20= 7m$
$2m=20$
$\implies   \ m=10$

The Milky Way Galaxy has 

physics the universe types of galaxies galaxies constellations

  1. elliptical shape

  2. spiral shape

  3. irregular shape

  4. none of these

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Correct Option: B
Explanation:

Milky Way is spiral in shape.

Fill in the blank:
A vast collection of billions of stars is called a _______.
physics the universe types of galaxies galaxies constellations

  1. universe

  2. galaxy

  3. constellation

  4. none of the above

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Correct Option: B
Explanation:
Galaxy is a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
Earth is is Milky way galaxy.

According to best estimates today, how old is the universe ?

physics the universe types of galaxies galaxies constellations

  1. between ten and twenty thousand years.

  2. between ten and twenty million years.

  3. between ten and twenty billion years.

  4. between ten and twenty trillion years.

  5. between ten and twenty quadrillion years.

Show answer
Correct Option: C
Explanation:

The age of universe is approximately 13.82 billion years. It is the time that has passes since the Big Bang that started the building of matter, time and space itself. Time had no existence before the Big Bang.
Hence correct answer is option C.

Which of the following provides clear evidence that the universe is expanding ?

physics the universe types of galaxies galaxies constellations

  1. the Oort cloud

  2. the Kuiper belt

  3. Saturn's ring

  4. Halley's comet

  5. the red shift of distant galaxies

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Correct Option: E
Explanation:

The spectrum of light coming from galaxies have spectral lines of hydrogen ,sodium etc. We compare the spectral lines obtained from galaxy to the spectral lines obtained in laboratory of the same element .If the spectral lines of galaxy are shifted towards the red end of the spectrum (red shift) it means the galaxy is going away from earth . This implies that universe is expanding .This is one of the applications of Doppler's effect .

Community or collection of stars is called:

physics the universe types of galaxies galaxies constellations

  1. solar system

  2. galaxy

  3. planet

  4. milky way

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Correct Option: B
Explanation:

The solar system is the planetary system, where we live. It consists of the Sun and its planets, including the Earth.

A galaxy is a collection of millions of stars which are bound together to form a specific shape.
Planet is a body which revolves around a star. For eg:- The earth is a planet of the Sun which is a star.
Milky Way is the name of our galaxy. The sun and the earth are in the Milky Way.

The galaxies are usually classified on the basis of their:

physics the universe types of galaxies galaxies constellations

  1. Mass

  2. Size

  3. Shape

  4. Any one of the above

Show answer
Correct Option: C
Explanation:

Galaxies are defined on the basis of their shape.